The present work focuses on investigations of a highly selective ligand for Am(III)/Ln(III) separation: bis-triazinyl-pyridine (BTP). By means of nano-electrospray mass spectrometry, complex formation of BTP with selected elements of the lanthanide series is investigated.
We show that the diluent drastically influences complex speciation. Measurements obtained in the extraction-relevant diluent 1-octanol show the occurrence of Ln(BTP)i (i = 1¿3) species in different relative abundances, depending on the lanthanide used. Here, the relative abundances of the Ln(BTP)3 complexes correlate with the distribution ratios for extraction to the organic phase of the respective lanthanide.